The present application relates to a nonaqueous electrolytic solution and to a battery. In more detail, the present application relates to a nonaqueous electrolytic solution containing an organic solvent and an electrolyte salt and to a battery using the same.
In recent years, portable electronic appliances such as a video camera, a mobile phone and a laptop personal computer have widely spread, and it is strongly demanded to realize downsizing, weight reduction and long life thereof. Following this, the development of batteries as a power source for portable electronic appliances, in particular, secondary batteries which are lightweight and from which a high energy density is obtainable is advanced.
Above all, secondary batteries utilizing intercalation and deintercalation of lithium for a charge/discharge reaction (so-called lithium ion secondary batteries) are largely expected because a high energy density is obtainable as compared with lead batteries and nickel-cadmium batteries.
Such a secondary battery is provided with an electrolytic solution containing a solvent and an electrolyte salt dissolved therein. As this solvent, mixed solvents obtained by mixing a high-dielectric constant solvent which is easy to solvate with the electrolyte salt (for example, ethylene carbonate, propylene carbonate, etc.) and a low-viscosity solvent with excellent ion conductivity (for example, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, etc.) are widely used. Since characteristics of the lithium secondary battery are largely influenced by a nonaqueous electrolytic solution to be used, for the purpose of more enhancing the battery characteristics, there are proposed nonaqueous electrolytic solutions containing various compounds.
For example, as described in Patent Document 1 (JP-A-2006-86058), there is proposed a method in which by adding a halogenated cyclic carbonate such as fluoroethylene carbonate or a cyclic carbonate having a carbon-carbon multiple bond such as vinylene carbonate to an electrolytic solution, a coating is formed on a negative electrode surface, and a reaction of a negative electrode active material with the electrolytic solution, or the like is suppressed, thereby improving a charge/discharge efficiency. Also, as described in Patent Document 2 (JP-A-2007-141830), there is proposed a method in which by incorporating a difluorophosphate which is a kind of an electrolyte salt together with the previously described reactive cyclic carbonate, even when a small amount of vinylene carbonate is incorporated, a cycle characteristic is enhanced, thereby enabling it to make compatible with a good low-temperature characteristic.